President Barack Obama pauses for a moment as he speaks from the White House regarding the bombings at the Boston Marathon, Monday, April 15, 2013. The attack coincides with both Patriots’ Day in Massachusetts and federal Tax Day.

Monday, the Boston Marathon was brought to a disastrous end by a sudden explosion that killed three people and injured at least 144 more. Two bombs filled with ball bearings detonated 12 seconds apart near the finish line at 2:50 p.m. Eight-year-old Martin Richard was among those killed. White House officials believe it to be an act of terrorism. The attack coincides with Patriots’ Day in Massachusetts. No suspect has been identified.

“There is no suspect. There are people we’re talking to,” said Boston Police Commissioner Edward Davis.

Across the United States, police departments in major cities went on high alert. These include New York and Washington, both attacked on Sept. 11, 2001. This is the worst bombing on U.S. soil since then.

The FBI has begun an investigation into the attack involving both state and local police. Late Monday into early Tuesday, law enforcement officials searched an apartment at 364 Ocean Avenue in the Revere suburb of northern Boston. They removed brown paper bags, two trash bags and a duffel bag. Massachusetts State Police confirmed the search was related to the bombings.

The apartment reportedly belongs to 20-year-old Abdul Rahman Ali Alharbi. The Saudi national is believed to have entered the U.S. on a student visa, formerly attending the New England School of English. Alharbi is currently a “person of interest” and not a suspect. His leg was injured during the incident and he is currently being treated at a local hospital under guard. This has been independently confirmed by both CNN and FOX News.

The Boston Police Department has issued two alerts: One regards a rental van, which may have tried to access the marathon route. The other concerns a “darker-skinned or black male” wearing a backpack, dark clothing and a hooded sweatshirt seen trying to enter a restricted area about five minutes before the first explosion.

Massachusetts Gov. Deval Patrick said in a statement shortly after the attack, “This is a horrific day in Boston. My thoughts and prayers are with those who have been injured. I have been in touch with the president, Mayor Menino and our public safety leaders. Our focus is on making sure that the area around Copley Square is safe and secured. I am asking everyone to stay away from Copley Square and let the first responders do their jobs.”

Hours after the attack, President Barack Obama said from the White House, “We still do not know who did this or why. And people shouldn’t jump to conclusions before we have all the facts. But make no mistake. We will get to the bottom of this. And we will find out who did this. We will find out why they did this. Any responsible ─ any responsible individuals, any responsible groups will feel the full weight of justice.”

Victims of the blasts were either treated on scene or at eight different hospitals, including Brigham and Women’s Hospital, and Children’s Hospital Boston. The injured included 17 in critical condition and 25 in serious condition. At least 10 of the wounded required amputation of limbs. At least eight of the injured are children. The youngest of them is three-years-old according to The Boston Globe.

A mile marker during the course of the 26.2-mile race was dedicated to honoring the victims of the Newtown, Conn. shootings at Sandy Hook Elementary School. Joanne Flaminio, president of the Boston Athletic Association, previously said the 26 miles commemorate the 26 who died.

Update

Friday, April 19, authorities confronted two suspects in an explosive interchange in Watertown, Mass. One suspect was shot dead, former boxer Tamerlan Tsarnaev. His brother, 19-year-old Dzhokhar Tsarnaev, escaped briefly but has been brought into custody. Operating via a local tip from a concerned neighbor, the younger Tsarnaev was found hiding under an upturned boat.